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Mathematics 21 Online
OpenStudy (anonymous):

WILL FAN+MEDAL!!!!!!!!

OpenStudy (anonymous):

Use function notation to write the equation of the line. f (x) = – x – 1 f (x) = –2x – 1 f (x) = 2x – 1 f (x) = –2x + 1

OpenStudy (mathstudent55):

What is the y-intercept? That means: At what y-value does the line cross the y-axis?

OpenStudy (anonymous):

1

OpenStudy (anonymous):

@mathstudent55

OpenStudy (mathstudent55):

Are you sure. It is 1 unite BELOW the x-axis. Are you sure that is 1?

OpenStudy (anonymous):

Yes

OpenStudy (mathstudent55):

Are you sure. It is 1 unit BELOW the x-axis. Are you sure that is 1?

OpenStudy (mathstudent55):

Wouldn't is be -1?

OpenStudy (anonymous):

Let me look.

OpenStudy (anonymous):

Ok yeah -1 sorry

OpenStudy (mathstudent55):

|dw:1445973824398:dw|

OpenStudy (mathstudent55):

Ok. We have a y-intercept of -1. The slope-intercept form of the equation of a line is: \(y = mx + b\) where b is the y-intercept. Since we can see from the graph that the intercept is -1, we can replace b with -1. Our equation is going to be: \(y = mx - 1\) Now we need to find m, the slope.

OpenStudy (mathstudent55):

BTW, we can already eliminate choice D, since choice D uses 1 for the y-intercept instead of -1.

OpenStudy (anonymous):

2

OpenStudy (mathstudent55):

Now we need to read the slope off the graph. To do that, we need to find two points on the line that are easy to read. Easy to read points on a line are points where the line passes over a grid intersection.

OpenStudy (mathstudent55):

The slope is not 2. We are going to find it very soon.

OpenStudy (mathstudent55):

Can you read a point of the line that is easy to read?

OpenStudy (anonymous):

-2

OpenStudy (mathstudent55):

|dw:1445974185803:dw|

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